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Reverse / invert a dictionary mapping
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For Python 2.7.x
inv_map = {v: k for k, v in my_map.iteritems()}
For Python 3+:
inv_map = {v: k for k, v in my_map.items()}
share
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improve...
Cocoa Core Data efficient way to count entities
...n do with SELECT count(1) ...). Now I just solved this task with selecting all with NSFetchedResultsController and getting the count of the NSArray ! I am sure this is not the best way...
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Double Negation in C++
...ernel). For GCC, they're implemented as follows:
#define likely(cond) (__builtin_expect(!!(cond), 1))
#define unlikely(cond) (__builtin_expect(!!(cond), 0))
Why do they have to do this? GCC's __builtin_expect treats its parameters as long and not bool, so there needs to be some form of conver...
How to close current tab in a browser window?
...ndow.close();
or you can specify a different window.
So:
function close_window() {
if (confirm("Close Window?")) {
close();
}
}
with HTML:
<a href="javascript:close_window();">close</a>
or:
<a href="#" onclick="close_window();return false;">close</a>
You r...
Passport.js - Error: failed to serialize user into session
...d serializing user information but only id's (for bloat/perf reasons personally).
– electblake
Jan 22 '16 at 20:03
2
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What is mattr_accessor in a Rails module?
I couldn't really find this in Rails documentation but it seems like 'mattr_accessor' is the Module corollary for 'attr_accessor' (getter & setter) in a normal Ruby class .
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Why so red? IntelliJ seems to think every declaration/method cannot be found/resolved
I just installed and re-installed IntelliJ. Every Java file is coming up RED. I checked the JDK; it is at 1.6.##. The maven clean install build worked just fine.
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Get all directories within directory nodejs
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Here's a shorter, syncronous version of this answer that can list all directories (hidden or not) in the current directory:
const { lstatSync, readdirSync } = require('fs')
const { join } = require('path')
const isDirectory = source => lstatSync(source).isDirectory()
const getDirectori...
Fastest way to extract frames using ffmpeg?
... @Evi1M4chine just remove the -r parameter this will extract all frames
– studioj
Nov 15 '16 at 6:14
14
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Remove a string from the beginning of a string
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Plain form, without regex:
$prefix = 'bla_';
$str = 'bla_string_bla_bla_bla';
if (substr($str, 0, strlen($prefix)) == $prefix) {
$str = substr($str, strlen($prefix));
}
Takes: 0.0369 ms (0.000,036,954 seconds)
And with:
$prefix = 'bla_';
$str = 'bla_string...